What are the management strategies for Acute Respiratory Distress Syndrome (ARDS)?

Management of Acute Respiratory Distress Syndrome (ARDS)

The cornerstone of ARDS management is lung-protective mechanical ventilation using lower tidal volumes (4-8 ml/kg predicted body weight) and lower inspiratory pressures (plateau pressure ≤30 cmH2O), along with prone positioning for more than 12 hours per day in severe ARDS. 1, 2

Ventilation Strategies Based on ARDS Severity

For All ARDS Patients:

• Lung-protective ventilation:
  • Tidal volume: 4-8 ml/kg predicted body weight 1, 2
  • Plateau pressure: ≤30 cmH2O 1
  • Driving pressure: target <14-15 cmH2O 2
  • Calculate predicted body weight using:
    • Men: PBW = 50 + 2.3 (height in inches - 60) kg
    • Women: PBW = 45.5 + 2.3 (height in inches - 60) kg 2

PEEP and FiO2 Management by ARDS Severity:

1. Mild ARDS (PaO₂/FiO₂ 201-300 mmHg):

   • Lower PEEP (5-10 cmH₂O)
   • Target PaO₂ 70-90 mmHg, SpO₂ 92-97% 2

2. Moderate ARDS (PaO₂/FiO₂ 101-200 mmHg):

   • Higher titrated PEEP (8-12 cmH₂O)
   • Consider recruitment maneuvers (conditional recommendation) 1, 2

3. Severe ARDS (PaO₂/FiO₂ ≤100 mmHg):

   • Higher titrated PEEP (12-15+ cmH₂O)
   • Consider lower SpO₂ targets (88-92%) with high PEEP requirements
   • Prone positioning for >12 hours/day (strong recommendation) 1, 2
   • Consider neuromuscular blockade for 48 hours 2, 3

Adjunctive Therapies

Strongly Recommended:

• Prone positioning for severe ARDS (PaO₂/FiO₂ ≤100 mmHg) for >12 hours/day 1, 2
• Conservative fluid management for patients without tissue hypoperfusion 2, 3
• DVT and stress ulcer prophylaxis 2

Conditionally Recommended:

• Corticosteroids to reduce inflammatory response and pulmonary edema 2
• Recruitment maneuvers in moderate or severe ARDS 1
• Enteral nutrition when appropriate 2
• Venovenous ECMO for selected patients with severe ARDS refractory to conventional therapy 2, 3

Not Recommended:

• High-frequency oscillatory ventilation in moderate or severe ARDS (strong recommendation against) 1
• Inhaled nitric oxide (suggested against) 3

Monitoring and Adjustments

• Monitor dynamic compliance, plateau pressure, and driving pressure regularly 2
• Calculate mechanical power (aim for ≤17 J/min) 2
• Assess for auto-PEEP and flow limitation 2
• If respiratory acidosis develops from low tidal volume strategy:
  • Reduce ventilation circuit dead space
  • Increase respiratory rate
  • Consider extracorporeal CO₂ removal in selected cases 4

Weaning and Liberation from Mechanical Ventilation

• Initiate weaning as soon as clinically appropriate 2
• Perform daily spontaneous breathing trials when ready 2
• Consider non-invasive ventilation post-extubation in selected patients 2

Clinical Pitfalls and Caveats

1. Underrecognition of ARDS is common, leading to underutilization of evidence-based interventions 1

2. Predicted body weight approach is imperfect as it doesn't account for variations in aerated lung due to inflammation, consolidation, flooding, and atelectasis 4

3. Respiratory acidosis may result from low tidal volume strategy and requires appropriate management 4

4. Post-ARDS complications include diminished functional capacity, mental illness, and decreased quality of life, requiring ongoing care 5

5. Avoid excessive fluid administration unless needed for tissue perfusion, as this can worsen pulmonary edema 2, 3